In recent years, there has been developed, as a suspension system for a vehicle, the so-called electromagnetic suspension system including an electromagnetic actuator configured to generate, with respect to a sprung portion and an unsprung portion, a force in a direction in which the sprung portion and the unsprung portion are moved toward and away from each other, based on a force of an electromagnetic motor. For instance, the following Patent Document 1 discloses such an electromagnetic suspension system. The disclosed suspension system is expected as a high-performance suspension system in view of an advantage that it is possible to easily realize a vibration damping characteristic based on the so-called skyhook theory because the suspension system can generate a propulsive force with respect to a relative movement of the sprung portion and the unsprung portion.    Patent Document 1 JP-A-2007-203933